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Comment Re:The Fictional Radioactive Materials (Score 1) 242 242

...You can't make any money on it. But Boeing is taking out patents. So, the only conclusion is that Boeing has stumbled onto an idea that will make fusion engines a practical reality before the patent runs out.

Here's another conclusion - Boeing has decided that the publicity for this patent is worth the cost of filing it. Or that the corporate inventor and patent attorneys find that this is a good way to keep their jobs funded (not exclusive with the previous possibility). Somehow these seem far more likely than a secret new technology nobody else has dreamed of (and is not evident in the actual patent).

Comment Re: WHAT radioactive materials? (Score 1) 242 242

Laser initiated fusion works just fine. It's just not net energy positive. But you don't need it to be when you're just using it as a neutron source. The fission reaction it kicks off is enthusiastically energy positive.

For some extremely unusual definitions of "fine" perhaps. At least it exists, which may be the very low bar you are setting for "fine".

This paper reports on the current state of the art of laser initiated fusion. The accomplishment was to get slightly more energy (about 14 kJ) out the D-T fuel (~30% more) that was deposited in the fuel itself. This was less than 1/10 the laser beam energy delivered to the capsule though (150 kJ).

Although fission, produced by a fusion neutron, produces more energy than the fusion reaction itself, the ratio is about 17-fold, which just barely compensates for the current low yield relative to the laser pulse. Meanwhile the best available lasers for this type (ultra-short tailored pulses) are 0.5% efficient, and the ability to convert fission heat into electricity to drive the laser in the aircraft would be on the order of 10%, and then we need this system to perform at much larger than system break-even levels to drive an actual aircraft. Fusion energy schemes typically assume a yield advantage larger than 10-1 (usually 100-1) to make the system a viable energy producer. So we are short by a factor of 100,000 or so in terms of system capability (fusion explosion round trip back to laser pulse generation) to support the concept. There are plans to upgrade the laser using diode pumps, which should improve its efficiency by a factor of 6, which helps, but that hardly puts a major dent in the short fall.

Oh, and the laser currently is as large as a sports stadium, and can only fire a few shots a day, instead of hundreds per second (a 1,000,000-1 repetition rate shortfall) and the fusion target is made out of gold and costs $10,000 per shot (the amortized cost per shot given the cost of the whole facility to do it is on the order of a million dollars). Factoring in the enormous decrease in target costs (factor of 100,000 say) and size of the laser (lets say a factor of 10,000 to fly it), we are looking at a figure-of-merit short fall of something like 20 orders of magnitude to turn the concept into reality. But other than that laser fusion works just fine.

Comment Re:Big giant scam ... (Score 1) 843 843

Surprisingly enough, the production line is not gone, though it is shut down. The decision to shutdown production was coupled with a deliberate decision to preserve the F-22 production capability for possible reactivation. The estimated cost for reactivation of the mothballed line is on the order of 200 million dollars, the cost of one or two aircraft.

If you think it really can be restarted for $200 million (this is the US Military Industrial Complex we're talking about), then I've got a bridge to sell.

If we have 1 to 2 years warning, sure, we might be able to do that...

What happens if we have 6 weeks warning?

Well the fly-away cost for two F-22s is $300 million, so I was already providing for some cost growth. And, sure, I would not be surprised if it was more - nonetheless that is the quoted estimate.

Even 1-2 years is not enough lead-time. The lead-time from order to delivery when the line was running was 3 years. Add to that the reactivation time (perhaps that could be collapsed into the normal lead time though as the full line wanted be needed initially). And the production rate was 24 a year. So to double the fleet would take at least a decade.

It would not be the response to a sudden emergency, but to a longer term assessment of the strategic situation.

Comment Re:Big giant scam ... (Score 1) 843 843

Sure, but we didn't buy enough F-22s.

The production line is gone, shut down, history... If we have to fight someone who can actually fight back, such as Russia or China, those F-22s will simply be too few to do much.

How many would have been the "right" number? One of the principle reasons that production was curtailed was that projected threats from Russian and China did not materialize.

Surprisingly enough, the production line is not gone, though it is shut down. The decision to shutdown production was coupled with a deliberate decision to preserve the F-22 production capability for possible reactivation. The estimated cost for reactivation of the mothballed line is on the order of 200 million dollars, the cost of one or two aircraft. So if a real need for the F-22 were to appear then it would be possible to put it back into production. This is really the best of both worlds: we avoid sinking tens of billions into likely unneeded excess inventory, while still having the capability to produce more if a demonstrated need arises.

See: http://www.fas.org/sgp/crs/wea...

Comment Re:"as a means to raise awareness ..." (Score 1) 76 76

Depends on what the term "killer asteroid" means. For a once-in-five-hundred-thousand-year civilization destroying asteroids larger than 1 km we have already identified all of them. Possible threats from this population can be projected developing centuries in the future.

For the less extreme threats in the ranges from 100 meters to 1000 meters (which covers impacts in an energy range from 100 megatons to 100,000 megatons) we do have a good way to go, but we are closing in on a 90% detection rate for the larger members of this group.

A 100 meter, 100 megaton asteroid can destroy a city, if it hits it, but is only a localized threat. The large majority of such impactors will cause little or no loss of life since only about 1% of Earth's surface is urbanized. Unless the target is a city the most practical means of dealing with the threat will be local evacuations. For this size a month's warning should be sufficient to deal with the situation. This size can also be completely destroyed by a nuclear explosion, so that a ready-for-launch strategic-sized nuclear warhead could be employed.

A significant fraction of severe threats can never be handled by an Earth-surface survey program - the threat posed by long period comets. This represents as much as 20% of the total threat, but these can only be detected effectively by space-based infrared telescopes, and the warning we will get will only be a couple of years in advance as they approach from the outer reaches of the solar system.

Comment Re:quotation marks (Score 1) 424 424

The solution, then, is to understand how Google treats punctuation within even a quoted string and modify your search accordingly.

That solution would be a much better solution if the rules for how Google treats punctuation were explicit, easily discoverable and consistent.

If you can point me to a page of documentation revealing these rules, I will appreciate it. Googling for it (assuming it exists) has so far been unsuccessful.

In fact the bit about "consistent" we know is not true, since Google tells us it isn't:

  • "Except for the examples below, Google Search usually ignores punctuation" (usually means unspecified exceptions),
  • and
  • "Even though you can use the punctuation marks below when you search, including them doesn’t always improve the results. If we don't think the punctuation will give you better results, you'll see suggested results for that search without punctuation."
  • (We will ignore what you type whenever we think we know better than you.)

Comment Re:quotation marks (Score 3, Interesting) 424 424

I agree with AC. The comments by grimmjeeper and Spazmania here are bizarre.

The fact that "." has been used a wildcard in Kleene grammars, and used in regular expressions, is irrelevant.

There is nothing in Google's query instructions that suggests that search strings in quote are regular expressions, or is a Kleene grammar of any sort, or that a period is even a wildcard. It explicitly states that the asterisk is a wild card, no mention of a period.

Comment Re:two schools of thought rear their ugly heads (Score 1) 272 272

Deflection:possibly, but into what or where?

Easy: away from Earth. It is only the fact that at one point in its multi-billion year orbital history that it happens to come within 4000 miles of the Earth's center of mass that we care about. If we make it miss, by even a small distance, it will continue (typically) for billions of years more.

Asteroid deflections is really just a process of cosmic sheepherding - keeping the orbits of the big rocks from becoming (and remaining) Earth intercepting ones.

Comment Re:Way Premature - And Probably Unnecessary (Score 1) 272 272

Actually I should have simply said that only "one system be kept ready", not that only one should be built. So make it two, even three for back-up. Well established launch systems have reliability rates of 95%, so high levels of redundancy are not really called for. Still not 10-20. And it still only is needed for one corner case of relatively small threat magnitude. More serious threat call for special missions and have threat timelines long enough to organize them.

Actually testing the interception system was stipulated, but having tested it, you know how to build more.

Comment Way Premature - And Probably Unnecessary (Score 2) 272 272

There are wide variety of possible cosmic collision threats - with only rare once-a-century (or less frequent) size events being candidates for any sort of deflection scheme. More frequent ones we can absorb with minimal damage. The 2013 Chelyabinsk event was a 20 meter class asteroid, and we get hit with a few of these a year. Even a repeat of the Chelyabinsk over a much larger city would not be catastrophic, as a natural catastrophe it might rank as a "major storm" in terms of damage potential.

It is larger asteroids, above the 20 meter size, that are destructive enough to consider an international interception mission.

Barringer Crater in Arizona is an example of a 50 meter object (a once in a millennium event), such an impact would be highly destructive in a populated area. Current collision threat programs have identified 96% of the "civilization ender" 1+ km class objects (once in a million year event), and are moving toward identifying 90% of the 140 meter class (once in 10,000 years).

The ideal method dog dealing with any collision threat is to detect it long in advance, accurately measure its trajectory, and then modify it just enough to avoid a predicted collision years later (perhaps many decades later, even centuries later for really big ones). Smaller objects need smaller nudges and can be diverted at later dates than big ones. An aggressive monitoring system is the first line of defense, without detection there can be no defense, and the better your detection the easier deflection becomes, and the cost of monitoring is much less than a single interception mission.

A variety of nudging techniques have been proposed: kinetic collision diversion, gravity attractor tugs, and nuclear deflection schemes primarily, but all of them are in early stages of development and have some promise. Different deflection schemes might be needed based on the nature of the threat object (size, physical nature, etc.).

Until we have candidate defection systems to evaluate, and actually test, it is way premature to discuss storing nuclear devices for this purpose. Probably storing a ready made device would be of no value. When we detect a threat requiring deflection we would first need to organize the whole launch and space probe project, which would likely take a few years (assuming warning times on the order of decade) during which time a nuclear device customized to the mission could be manufactured as needed. If the world decides (after suitable development and testing) that a ready-to-launch-on-short notice vehicle is a good idea to deal with small threats detected months in advance, and it is determined that a nuclear device is the proper technique, then we would only need one such system to be built and kept ready - with a grand total of one special purpose nuclear device.

Comment Re:HÃ? (Score 0) 419 419

In reality, people with occupational radiation doses have lower cancer rates than the general population.

Which is due to the "healthy worker" effect. People who qualify for working in the strictly regulated occupational radiation environments are healthier inherently than the general population.

In fact, there is NO valid example of a LNT toxin in nature. If you reduce the concentration of any toxin in, say, water, there is always a point at which its medical impact drops to zero while there is still some toxin present. This is because natural selection ensures that we can survive the amount of that toxin that we normally find in the environment. This includes the constant drizzle of background radiation that we live in.

In fact, the scientific term for belief in LNT in chemistry is "homeopathy."

Since everyone is subject to background radioactivity, the situation where there is only a tiny radiation exposure and nothing more does not exist. In reality everyone is exposed to significant background radiation, and added exposure sources are in addition to that ever-present background. So the "LNT scoffers" here are claiming sure knowledge that background radiation itself contributes nothing at all to natural cancer occurrence, which is essential to support their belief that small additional increases in radiation also have zero effect. This is something that is in flat denial of radiation biology.

Lots of people get exposed to natural sources of toxic substances that have real medically observable bad effects on them. Excessive natural exposures to arsenic, cadmium, mercury, lead, fluoride ion, in addition to various natural organic compounds, causing serious health problems are all well known, and if you take anyone affected by one of these, add even a tiny additional amount of the toxic substance to their intake, you can expect to get a real increase in harm, however small.

Comment Re:Concept itself is flawed (Score 1) 169 169

The same logic applies in the military to the people who volunteer for suicide missions and hopeless last stands, and yet those have happened on a number of occasions, often to good effect, and always for a lesser cause than bringing humanity to a second planet.

I notice that you did not cite any such cases. Do you actually know of any, of you just assuming based on... what?

A "hopeless last stand" in which you find yourself facing near-certain death due to battlefield reverses (ambush, surprise attack, collapse of a defense perimeter, etc.) is not the same as a "suicide mission" in which someone who is not in imminent danger of being killed otherwise, is sent out to die on purpose. In fact, people survive "hopeless last stands" on occasion.

Genuine suicide missions are also quite rare for Western societies even in wartime. These certainly happened during WWII, with the Japanese and Soviets at least, but a high chance of dying in a mission is quite different from a mission which has no other possible outcome. Even suicide bombers have a significant chance of not dying, given the failure rate of suicide bombs.

This sort of "mission", sending volunteers to a certain death (no other possible outcome) without any necessity, in peace time, is unknown in any modern Western society as far as I am aware. Having a private organization do it makes it a criminal act.

Comment Re: Walks like a duck, quacks like a duck... (Score 1) 169 169

Meant to be ironic - but reveals idiocy just as the OP said. Good to remain anonymous, coward.

With this "mission" the chances of death are certain - there is no other possible outcome. This makes it more dangerous than being a suicide bomber, since with that mission there is a chance the bomb will fail to explode (and this has happened many times).

When has the U.S. government in peace time sent any civilian on a genuine, absolutely certain suicide mission? NASA certainly never has. You would be hard put to find any military missions that fit that description, even in wartime.

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